Means for altering the reflection of radar waves



Feb, 24, w45.` A. KQRM- ET AL '2,436,578

MEANS .FOR .ALTERING THE REFLECT'ION OF RADAR WAVES Filed March 4, 1944`IN V EN TORS AE THUR K ORN. JSfP/-l W H555.

/MON L RUSK/N,

A TTOENE K Patented Feb. 24, 1948 RIEAN S FOR ALTERING THE REFLECTION FRADAR WAVES Arthur Korn, Hoboken, N. J., and Joseph W. Hess and Simon L.Ruskin, New York, N. Y.; Adele Hess, administratrix of said Joseph W.Hess, deceased; Elizabeth P. Korn, administratrix of said Arthur Korn,deceased; assignors to said Ruskin Application March 4, 1944, Serial No.524,9991,

(Cl. Z50-1.76)

3 Claims.

I It is known that radar measurements and calculations make it possibleto locate objects, such as airplanes with respect to their distance,altitude and azimuth from a place of observation.

The radar methods are based on the laws governing the propagation ofvery short electric waves, Such waves are sent from the place ofobservation in the direction towards the object and reected from thisobject. The reflected waves interfere vwith the original waves and fromthis interference a conclusion can be drawn in respect to the positionof the moving object. Such measurements are for example also used foraiming antiaircraft guns against planes. Such attacks by guns areintended to destroy an aircraft before it drops its bombs or to destroyit so that it cannot get away safely and return with a fresh load ofbombs.

The aforesaid radar methods having developed in this War in such a highdegree that mass attacks of planes have to count in making with verylarge losses.

According to the present invention devices and methods are provided,whereby the measurements by radar become less readily detected. Thismethod in general consists inmaking the radar waves sent from theirsource strike upon reiiecting surfaces which contain certainelectrically semi-conducting material whereby the reflected radar wavesare altered and cause thereby erroneous radar measurements.

The composition of the electrically semi-conducting material and itsstructure, and also the method and devices for making l-ess readilydetected the customary radar measurements can be varied Without changingthe spirit of the invention.

In the following some examples for the composition of the electricallysemi-conducting ma terials and the aforesaid methods and devices aredescribed.

It has been found that one electrically semiconducting material for theaforesaid purpose is cuprous oxide (CuzO) which can be used toadvantage. The cuprous oxide can be applied in form of a layer on a verythin moldable copper sheet or wire by annealing the copper sheet or wirein a furnace in an atmosphere of oxygen at a temperature ofapproximately 800-1000 Celsius.

It has been found that sensibly altered reflections of radio waves areobtainable by using a basic body of copper (sheet or wire) carryinglayers of other materials such as silver, tin, gold and then subjectingthis body to an annealing 2 temperature by which cuprous oxide isobtained in one of the aforesaid metal laminations. By this process verysensible reflectors can be made with variations of the alterations ofthe reections of the radio waves.

It has been further found that reflectors for altering the reflection ofradar waves can be made of powdered cuprous oxide. Such powdered cuprousoxide is for example produced by annealing a mixture of copper chipsmade by filing, with black copper oxide in a covered Crucible. Thiscuprous oxide powder after being compressed has good ductility and canif desired be drawn in form of Wires.

It has been further found that reflectors for altering radio waves canbe built of knitted or woven texture, plaited work or net work of wires,or strips having a surface of cuprous oxide or in their interiors coresor layers of cuprous oxide.

Reflectors for altering the reflection of radio waves can also beproduced by embedding electrically semi-conducting material such aspowder of cuprous oxide in pasty or liquid material, capable of beingsolidified or hardened aftervthe embedding of electricallysemi-conducting material. As such embedding masses can be used forexample plastics, shellac, resins, glues and some oil paints.

It is advantageous to use for all the above applications pureelectrolyt-ic copper in the :form of sheets, wires and powders.

Instead of cuprous oxide the metallic form of selenium and tellurium canbe used for the construction of reflectors altering the reflection ofradio waves. For the production of such reflectors, for example seleniumin a very thin layer is joined by casting on a thin metal sheet or wireand then by annealing brought into its metallic modification.

The foregoing cuprous oxide and selenium and tellurium are the mostconspicuous members of the group of electrically semi-conductors, whichalter the reflection of radar waves efficiently.

By the aforesaid devices and methods the whole surface of a movingobject or only a part of the surface and also metallic parts ofcomplicated shape can be easily transformed into altering reflectors.

Although the invention as described above is clear in itself someexamples of this invention may be illustrated in the annexed drawingschematically.

Fig. 1 illustrates in enlarged scale a section of the surface structureof a metal body plated with one layer of semi-conducting material.

Fig. 2 shows in enlarged scale a section of the surface structure of ametal body painted with a compound of material containingsemi-conducting matter in `the form of powder or the like.

Fig. 3 illustrates a cross section through a wire plated withsemi-conducting material.

Fig. 4 is a top plan View oi a network consisting of metal wires platedwith semi-conducting material.

Fig. is a cross section of the network as illustrated in Fig. 4.

Fig. 6 illustrates in a schematical perspective View lthe principle ofthe invention.

In Fig. 1 the number l denotes .a part of a metallic body from whichradio waves are re flected. The body may be a metal sheet or a metalblock for example of copper. The number 3 denotes a layer of cup-reusoxide (CuzO). The number 2 denotes a zone of diffusion between the layerof cuprous oxide 3 and the surface of the copper body i. This zone 2 isformed automatically during the above described annealing treatment ofthe copper body.

In Fig. 2 the number i denotes a part of a metal body, l particles of apowder of semi-conducting material such as cuprous oxide (CuzO) and 5 asolidified embedding mass for said parti cles consisting as abovedescribed for example oi plastic, shellac, resins, glue or some oilpaints.

In Fig. .3 the number 6 denotes a copper wire, i a layer of cuprousoxide (CuzO) and 6 the Zone oi diffusion between the layer of couprousoxide and the surface of the copper wire.

In the Figs. 4 and 5 the number 2i) denotes the Warp wires and thenumber H the weft wires of the net work. Each of these wires comprises ametal core i4 consisting for example of copper and a covering layer l5consisting of electrically semi-conducting material for example ofcuprous oxide (CuzO).

In Fig. 6 the number 2b denotes an airplane, 2| a station emitting shortradio Waves w and 'u and 22 a station for the reception of the reflectedshort radio waves wx and the short radio waves 12.

In the known radio units the station 22 has been ordinarily arrangedeither close to the emitting station 2i or some distance of it. By thisknown equipment and known location methods the position of an airplane,with a surface reecting radar wave in normal manner, has hitherto beenfound.

According 'to the invention herein described the surface of parts ofairplanes, wings andbody are covered with a matter containingelectrically semi-conducting material, adapted to alter the reflectionof radio Waves from the ordinary path of reection. The short Wavesemitted by station 2| are reilected therefore according to the inventionin altered manner by the surface of the plane. Thus 'thereceivingfstation y22 fails to receive a normal amount of 'reflectedradio waves from the airplane 29. As a result the correct calculation ofposition of the airplane is weakened, because waves are directed to W1,W2, Ws, W4, W5, We, for example.

Having thus described in some details certain embodiments of theinvention what is claimed is:

1. The combination with a body forming a transport adapted to carryvarious loads and normally adapted to reflect radio waves, of a layer ofmetallic copper on the outer surface of said body and substantiallycovering it, and a second layer of cuprous oxide substantially coveringit, so that said layers distort impinging radio waves.

2. The combination `with a body forming a transport adapted to carryvarious loads and normally adapted to reflect radio waves, of a layer onthe outer surface of said body selected from the group consisting ofmetallic copper and metallic silver, and a second layer selected fromthe group consisting of cuprous oxide and metallic selenium, so thatsaidlayers distort impinging radio waves.

3. The combination with an airplane having a surface material normallyadapted to distort irnpinging'radio waves, of a layer on said outersurface selected from the group consisting of. metallic copper andmetallic silver and a second layer selected from the group consisting ofcuprous oxide and metallic selenium, so that said layers distortimpinging radio waves.

ARTHUR KORN. JOSEPH W. HESS. SIMON L. RUSKN.

REFERENCES CITED The following references are of record in the ille of.this patent:

UNITED STATES PATENTS Number .FOREIGN PATENTS Country Date Great BritainFeb. 11, 1935 Great Britain Dec. 9, 1938 Number Clark Oct. 16, 1917

